Ski boot

ABSTRACT

A ski boot includes a shell and a cuff which is hinged on the shell so as to rotate about a first axis substantially perpendicular to the center-plane of the boot. The ski boot is provided with a cuff locking device which includes: a fixing plate which is located on the shell substantially at the heel of the boot and is provided with a projecting pin which protrudes from the shell while remaining coaxial to a third axis which substantially lies on the center-plane of the boot, and is tilted with respect to the vertical by an angle from 60° to 90°; and a connecting arm which, in the area above the heel of the boot, extends astride between the rear part of the cuff and the fixing plate, while remaining on a lying plane substantially perpendicular to said first axis.

TECHNICAL FIELD

The present invention relates to a ski boot.

In greater detail, the present invention relates to an mountaineering or Telemark ski boot, use to which the following description explicitly refers purely by way of example without this implying any loss of generality.

BACKGROUND ART

As is known, more recent mountaineering ski or Telemark ski boots normally consist of a rigid shell made of plastic material, which is shaped so as to accommodate the skier's foot, and is provided at the bottom with a front sole and a rear heel usually made of non-slip elastomeric material; of a rigid cuff made of plastic material, which is shaped so as to embrace the lower section of the skier's leg from behind and is hinged to the upper part of the shell so as to rotate about a transversal reference axis substantially coincident with the articulation axis of the ankle; of an inner liner made of soft and thermal insulating material, which is removably inserted into the shell and the cuff, and is shaped so as to envelop and protect both the foot and the lower section of the skier's leg; and of an external protective tongue made of plastic material, which has the lower end hinged on the shell, immediately above the tarsus-phalanx area of the foot, and extends along the upper part of the shell up to reaching the cuff, so as to cover the longitudinal slit of the shell which allows/facilitates the temporary widening of the shell to insert the foot into the liner.

Mountaineering ski or Telemark ski boots are also provided with a series of manually-operated closing buckles, which are conveniently distributed on the shell and on the cuff, and are structured so as to selectively close/tighten the shell and the cuff so as to stably immobilize the skier's leg inside the liner.

Lastly, most mountaineering ski or Telemark ski boots are provided with a manually-operated cuff locking device which is structured so as to selectively

-   -   rigidly lock the cuff to the shell so as to prevent any swinging         movement of the cuff on the shell; or     -   completely release the cuff from the shell so as to allow the         cuff to freely swing both forwards and backwards about the         articulation axis of the ankle.

In more sophisticated mountaineering ski or Telemark ski boots, the cuff locking device comprises a rod or rigid connecting strut, which has the lower end hinged on the shell at the heel of the boot, so as to freely rotate about a reference axis locally substantially perpendicular to the center-plane of the boot, and extends on the center-plane of the boot up to reaching the portion of the cuff which is immediately above the heel of the boot.

The cuff locking device further comprises a mechanical strut locking member which is rigidly fixed to the cuff immediately above the heel of the boot so as to be engaged in an axially sliding manner by the upper part of the strut, and is structured so as to selectively prevent any relative movement between the strut and the locking member, thus rigidly connecting the cuff to the shell of the boot.

Unfortunately, although operating in an excellent way, a cuff locking device configured as such greatly limits the possibilities of adjusting the lateral tilt angle of the cuff. Adjustment that, if present, allows the user to best align the articulation axis of the two hinges connecting the cuff to the shell with the articulation axis of the user's ankle, thus making the use of the boot much more comfortable.

In fact, the lower end of the strut is hinged to the shell by means of a metallic pass-through pin which, unless mechanical assembly clearances, forces the strut to swing while remaining confined to the center-plane of the boot.

To provide the boot with the—albeit limited—possibility of adjusting the lateral tilt angle of the cuff, over the last few years certain mountaineering ski and Telemark ski boot manufacturers have decided to significantly increase the mechanical clearances between the lower end of the strut and the corresponding shell connecting pin, and to connect the cuff to the lateral sides of the shell by means of a pair of hinges which are structured so as to allow the user to vary the lateral tilt of the reference axis of the hinges by a few tenths of a degree.

Obviously, excessive mechanical clearance between the rigid strut and the pass-through pin which connects the strut to the shell does not allow the cuff locking device to prevent any relative movement between shell and cuff, with all the drawbacks this involves. In fact, even when the cuff locking device is in the locked cuff configuration, excessive mechanical clearances between the strut and the transversal pass-through pin connecting the strut to the shell allow small oscillations of the cuff with respect to the shell which have a negative effect on the dynamic behaviour of the boot when it is used in downhill skiing.

DISCLOSURE OF INVENTION

Aim of the present invention is to provide a cuff locking device which, when needed, is effectively capable of preventing any relative movement between the cuff and the shell, while allowing the lateral tilt angle of the cuff to be adjusted.

In compliance with the above aims, according to the present invention there is provided a ski boot as defined in Claim 1 and preferably, though not necessarily, in any one of the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings, which illustrate a non-limiting embodiment thereof, in which:

FIG. 1 is the side view, with parts removed for clarity, of an mountaineering ski boot made according to the teachings of the present invention;

FIGS. 2 and 3 show, in enlarged scale and with cross-sectioned parts and parts removed for clarity, the rear part of the FIG. 1 boot in two different operating positions; whereas

FIG. 4 shows, in enlarged scale and with cross-sectioned parts and parts removed for clarity, the rear part of the FIG. 1 boot in a second operating configuration.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to FIG. 1, number 1 indicates as a whole a ski boot, and in particular a ski boot specifically structured for practising the sports discipline of ski mountaineering or Telemark skiing.

Boot 1 essentially consists of an external rigid shell 2 made of plastic or composite material, which is shaped so as to accommodate the user's foot, and is provided at the bottom with a front sole 3 and with a rear heel 4, which are preferably, though not necessarily, provided with a treading profile and preferably, though not necessarily, made of anti-slip elastomeric material; and of a rigid cuff 5 made of plastic or composite material, which is preferably substantially C-shaped so as to embrace the lower part of the user's leg from behind, and is hinged on the upper part of shell 2 so as to freely swing about a transversal reference axis A, which is locally substantially perpendicular to the vertical centre-plane of the boot (i.e. perpendicular to the plane of the sheet in FIG. 1), and is also locally substantially coincident with the articulation axis of the user's ankle.

More specifically, cuff 5 is fixed in a freely rotatable manner to shell 2 by means of two connection hinges 6 which are arranged on the external and internal lateral sides of shell 2 and cuff 5, aligned along axis A, so as to allow cuff 5 to swing on shell 2 while always remaining on a reference plane which is orthogonal to axis A and substantially coincident with the center-plane of the boot.

The two hinges 6 are furthermore structured so as to allow a manual, micrometric adjustment of the tilt angle of axis A with respect to the vertical, that is to the vertical centre-plane of the boot, so as to allow the user to manually adjust the lateral tilt of cuff 5 and then align the reference axis A of the hinges to the articulation axis of the user's ankle according to the user's needs.

The above-described hinges 6 are components which are already widely known in the ski boot field, and therefore do not require further explanations.

With reference to FIG. 1, boot 1 is further provided with an inner liner 7 which is preferably made of soft and thermal insulating material, is housed inside shell 2 and cuff 5 preferably, though not necessarily, in removable manner, and lastly is shaped so as to envelop and protect the foot and the lower section of the user's leg; and with a protective, oblong-shaped tongue 8 which is preferably, though not necessarily, made of plastic or composite material, and is arranged resting on shell 2 in the area above the instep of the foot and the lower section of the leg, to cover a longitudinal slit (not shown) which extends along the upper part of shell 2, while remaining locally substantially coplanar to the center-plane of the boot, and allows the user to temporarily widen the upper part of shell 2 so as to introduce the foot more easily into liner 7.

In other words, the protective tongue 8 extends grazing the shell 2 above the instep of the foot, and then remount along the leg up to reach and insert below cuff 5, above the lower section of the tibia.

Lastly, boot 1 comprises one or more manually-operated mechanical boot-closing devices 9 which are structured so as to selectively close/tighten the shell 2 and cuff 5 so as to stably immobilize the user's leg inside boot 1; and a cuff locking device 10 which is structured so as to selectively:

-   -   rigidly lock cuff 5 to shell 2 so as to prevent any swinging         movement of cuff 5 on shell 2; or     -   totally release cuff 5 from shell 2 so as to allow cuff 5 to         freely swing both forwards and backwards about axis A.

In the example shown, in particular, the mechanical boot-closing devices 9 preferably, though not necessarily, consist of a series of lever closing buckles 9 which are arranged on shell 2 and/or on cuff 5 and/or on the protective tongue 8 so as to selectively close/tighten shell 2 and cuff 5, to stably immobilize the user's leg inside liner 7. Being components widely known in the field of ski boots, the closing buckles 9 will not be further described.

With reference to FIGS. 1, 2 and 3, the cuff locking device 10 instead extends astride shell 2 and cuff 5, immediately above the heel of the boot, and comprises:

-   -   a supporting plate 11 which is rigidly fixed to the rear part of         cuff 5, above the heel of the boot, so as to substantially lie         on the center-plane of the boot;     -   a fixing plate 12 which is rigidly fixed to shell 2,         substantially at the heel of the boot, so as to be aligned below         the supporting plate 11, i.e. so as to substantially lie on the         center-plane of the boot; and     -   a rigid, oblong connecting arm 13 which extends astride between         the supporting plate 11 and the fixing plate 12, while remaining         on a lying plane locally substantially coincident with the         centre-plane of the boot, that is substantially perpendicular to         the articulation axis A of hinges 6, and is hinged on the         supporting plate 11 so as to freely oscillate with respect to         the supporting plate 11 about a reference axis B locally         substantially perpendicular to the lying plane of the connecting         arm 13, that is locally substantially perpendicular to the         center-plane of the boot.

The fixing plate 12 is also provided with a projecting pin 14 preferably with a substantially circular cross-section, i.e. a pin which is substantially cylindrical or truncated-cone in shape, which protrudes from shell 2 while remaining coaxial to a reference axis C which substantially lies on the center-plane of the boot, is tilted with respect to the vertical by an angle α preferably ranging from 60° to 90°, and lastly is preferably locally substantially perpendicular to the surface of shell 2; and the lower end 13 a of the connecting arm 13 is shaped/structured so as to be inserted/fitted on the projecting pin 14 of the fixing plate 12 in an axially rotatable and easily releasable/extractable manner, so as to constrain the connecting arm 13 to the fixing plate 12 with the sole possibility of freely rotating about axis C of projecting pin 14.

More in details, with reference to FIGS. 2 and 3, the reference axis C of the projecting pin 14 is preferably, though not necessarily, tilted with respect to the vertical of an angle α ranging from 80° to 90°, and is also preferably oriented so as to be locally substantially perpendicular to the longitudinal axis L of the connecting arm 13.

The lower end 13 a of the connecting arm 13 is instead preferably provided with a hole or eyelet 14 a which is preferably, though not necessarily, of the pass-through type, and is shaped so as to be engaged in an axially rotatable and sliding manner by said projecting pin 14, so as to constrain the connecting arm 13 to the fixing plate 12 with the sole possibility of freely rotating with respect to the fixing plate 12 about axis C of projecting pin 14.

More specifically, in the example shown, the hole or eyelet 14 a is of a pass-through type, and has a circular section which is substantially complementary to that of the projecting pin 14, so as to be engaged in axially rotatable and axially sliding manner by the projecting pin 14.

Accordingly, when the lower end 13 a of connecting arm 13 is inserted/fitted on the projecting pin 14, the connecting arm 13 is capable of maintaining the supporting plate 11 at a predetermined, constant distance from the fixing plate 12, thus preventing any swinging of cuff 5 about the articulation axis A of hinges 6 and instead allowing cuff 5 to freely move/rotate with respect to shell 2 on a second reference plane P locally orthogonal to the vertical centre-plane of the boot.

With reference to FIGS. 1, 2 and 3, in the example shown, in particular, the supporting plate 11 is preferably made of metal material, and is preferably rigidly fixed to the rear part of cuff 5 in a rigid and stable, though easily releasable, manner.

In the example shown, in particular, the supporting plate 11 is rigidly fixed to the rear part of cuff 5 preferably, though not necessarily, by means of one or more transversal anchoring screws 15 (two screws in the example shown), each of which is sized so as to thoroughly engage a pass-through hole specifically made in the body of the supporting plate 11, and then to penetrate the body of cuff 5 to screw into a corresponding female screw body 16 located inside cuff 5, on the opposite side of the supporting plate 11, so as to keep the supporting plate 11 stably abutting on the rear part of cuff 5.

The supporting plate 11 is preferably also structured to be fixable to the rear part of cuff 5 in a plurality of distinct anchoring positions which are freely selectable by the user, so as to allow the user to vary/adjust the tilt angle of cuff 5 as required with respect to the vertical when the cuff locking device 10 locks cuff 5 to shell 2 so as to prevent any swinging movement of cuff 5 about axis A.

With reference to FIGS. 1 and 2, in the example shown, in particular, cuff 5 is preferably provided with an oblong, substantially straight-rack shaped base 17, which extends along the rear part of cuff 5 while remaining substantially coplanar to the center-plane of the boot, and the rear face 11 a of the supporting plate 11 is preferably provided with a toothed profile which is sized so as to stably mesh with any portion of the oblong base 17, so as to prevent any movement of the supporting plate 11 on the rear part of cuff 5.

The oblong base 17 with rack-like profile is also centrally provided with at least one long longitudinal pass-through slot or slit (not shown) which extends parallel to the center-plane of the boot, while remaining locally substantially coincident with the center-line of the oblong base 17; and each transversal anchoring screw 15 is sized so as to thoroughly engage the central slot or slit of the rack-profiled oblong base 17 and then screw into a corresponding female screw body 16 which is arranged abutting on the internal surface of cuff 5, on the opposite side of the oblong base 17, so as to keep the supporting plate 11 stably abutting on the oblong base 17 with rack profile.

Instead, the fixing plate 12 is preferably trapped in a rigid and stable, though easily removable manner, inside a pocket or seat specifically made on the surface of shell 2, at the heel of the boot.

Alternatively, the fixing plate 12 could also be embedded in a non-removable manner in the body of shell 2, at the heel of the boot.

Similarly to the supporting plate 11, in the example shown, the fixing plate 12 is also preferably made of metal material.

With reference to FIGS. 2 and 3, the connecting arm 13 instead preferably consists of a substantially straight-shaped, oblong rigid body 13, which is hinged like a rocker arm on the supporting plate 11 so as to freely oscillate about axis B, preferably, though not necessarily, by means of a transversal pass-through pin 18 which extends coaxial to axis B through the body of the connecting arm 13 and the body of the supporting plate 11.

The oblong rigid body 13 is also preferably made of metal material, and extends on the center-plane of the boot, preferably while keeping the initial portion substantially parallel and grazing to cuff 5, or better to the rack-profiled oblong base 17 arranged on the rear part of cuff 5, and the end portion of the connecting arm 13 locally substantially parallel and grazing to shell 2, or better to the fixing plate 12 which is integral with shell 2.

With reference to FIGS. 1, 2 and 3, the cuff locking device 10 is lastly provided with a manually-operated arm lifting mechanism 19 which is structured so as to selectively and alternatively arrange the connecting arm 13

-   -   in a totally lowered position (see FIG. 2) in which the lower         end 13 a of the connecting arm 13 is totally fitted/inserted on         the projecting pin 14 of the fixing plate 12, so as to prevent         any variation in the distance between the supporting plate 11         and the fixing plate 12; and     -   in a totally lifted position (see FIG. 3) in which the lower end         13 a of the connecting arm 13 is completely extracted and spaced         apart from the projecting pin 14 of the fixing plate 12, so as         to allow the connecting arm 13 and the supporting plate 11 to         freely move with respect to the fixing plate 13.

Obviously, when is in the totally lowered position (see FIG. 2), the connecting arm 13 prevents any swinging by cuff 5 about axis A. Instead, when is in the totally lifted position (see FIG. 3), the connecting arm 13 allows cuff 5 to freely swing on shell 2 about axis A.

With reference to FIG. 2, the arm lifting mechanism 19 preferably comprises an elastic member 20 which is structured so as to elastically maintain the connecting arm 13 stably in the totally lowered position; and a manually-operated control member 21, which is capable of displacing and stably maintaining the connecting arm 13 in the totally lifted position while overcoming the elastic thrust of the elastic member 20.

In the example shown, in particular, the elastic member 20 preferably consists of a helical spring 20 or the like, which is interposed between the supporting plate 11 and the upper end 13 b of the connecting arm 13 and is conveniently structured/sized so as to elastically oppose any reduction of the distance between the supporting plate 11 and the upper end 13 b of the connecting arm 13, thus always keeping the lower end 13 a of the connecting arm 13 abutting/adhering to the fixing plate 12.

The manually-operated control member 21 instead preferably consists of a lever 21 which is directly hinged on the connecting arm 13, on the side opposite to the elastic member 20 with respect to the rotation axis B of the arm, so as to freely rotate on the connecting arm 13 while preferably remaining on a reference plane locally substantially parallel or coincident with the lying plane of the connecting arm 13, and is shaped/structured so as to prop on/pivot on the supporting plate 11 immediately underlying and/or directly on the body of cuff 5 to force the connecting arm 13 to rotate about axis B from the totally lowered position to the totally lifted position, thus overcoming the thrust of the elastic member 20, so as to remove and move the lower end 13 a of the connecting arm 13 away from the projecting pin 14.

More in detail, the lifting lever 21 is provided with a cam-profiled lobed portion 21 a which, as the angular/tilting position of the lifting lever 21 with respect to the connecting arm 13 varies, is capable of resting on the supporting plate 11 or on the body of the underlying cuff 5, and then progressively increasing the distance between axis D and the supporting plate 11 or the underlying cuff 5, so as to force the connecting arm 13 to rotate about axis B from the totally lowered position to the totally lifted position, thus overcoming the thrust of the elastic member 20.

In the example shown, in particular, the lifting lever 21 is preferably made of metal or plastic material, and is also preferably hinged on the connecting arm 13 by means of a transversal pass-through pin 22 which extends through the body of the connecting arm 13 and the body of the lifting lever 21 while remaining coaxial to a reference axis D locally substantially parallel to axis B.

Additionally, the lifting lever 21 is preferably hinged on the connecting arm 13 at a first end, and has a second end shaped so as to be easily grasped by the user's hand. The cam-profiled lobed portion 21 a is preferably made at the first end of the lifting lever 21, and is preferably adapted to rest and slide on the supporting plate 11 without wearing down the plate surface.

Lastly, with reference to FIG. 4, the cuff locking device 10 preferably, though not necessarily, comprises a second rigid, oblong connecting arm 23 which has a first end 23 b structured so as to be fixable in a rigid and stable, though easily releasable, manner to the rear part of cuff 5, in place of the supporting plate 11, and a second end 23 a shaped/structured so as to be insertable/fittable on the projecting pin 14 of the fixing plate 12 in an axially rotatable and easily releasable/extractable manner, so as to constrain the connecting arm 23 to the fixing plate 12 with the sole possibility of freely rotating about axis C of projecting pin 14.

More in detail, similarly to the lower end 13 a of the connecting arm 13, the second end 23 a of the connecting arm 23 is preferably provided with a hole or eyelet 14 a which is preferably, though not necessarily, of a pass-through type, and which is shaped so as to be complementary to the shape of the projecting pin 14 and is adapted to be engaged in an axially rotatable and sliding manner by the projecting pin 14, so to constrain the connecting arm 23 to the fixing plate 12 with the sole possibility of freely rotating with respect to the fixing plate 12 about axis C of projecting pin 14.

With the aid of the second connecting arm 23, the cuff locking device 10 is therefore capable of permanently preventing any swinging of cuff 5 about the articulation axis A of hinges 6, however allowing cuff 5 to freely move/rotate with respect to shell 2 on a second reference plane P locally orthogonal to the vertical centre-plane of the boot.

Also the second connecting arm 23 is preferably made of metal material, and extends astride between the rear portion of cuff 5 and the fixing plate 12 preferably remaining on a lying plane locally substantially coincident with the center-plane of the boot.

With reference to FIG. 4, in the example shown, in particular, the first end 23 b of the connecting arm 23 is adapted to be rigidly fixed to the rear part of cuff 5 preferably, though not necessarily, by means of one or more transversal anchoring screws 25 (two screws in the example shown), each of which is sized so as to thoroughly engage a through hole specifically made in the body of the connecting arm 23, and then to penetrate the body of cuff 5 to screw into a respective female screw body 16 located inside cuff 5, so as to keep the first end 23 b of the connecting arm 23 stably abutting on the rear part of cuff 5.

Moreover, the first end 23 b of the connecting arm 23 is preferably structured to be fixable to the rear part of cuff 5 in a plurality of distinct anchoring positions which are freely selectable by the user, so as to allow the user to vary/adjust the tilt angle of cuff as required with respect to the vertical when the connecting arm 23 has its two ends fixed, one to cuff 5 and the other to fixing plate 12.

In the example shown, in particular, the first end 23 b of the connecting arm 23 is also preferably provided with a toothed profile which is sized so as to stably mesh with any portion of the oblong base 17, so as to prevent any movement of the supporting plate 11 on the rear part of cuff 5.

As is the case with the supporting plate 11, each anchoring screw 25 is sized so as to thoroughly engage the central slot or slit of the oblong base 17 with a rack profile, and then screw into a corresponding female screw body 16 which is arranged abutting on the internal surface of cuff 5, on the opposite side of the oblong base 17, so as to keep the first end 23 b of the connecting arm 23 stably abutting on the oblong base 17 with rack profile.

The operation of the ski boot 1 is easily inferable from the above description, and therefore does not require further explanations.

Instead, with regard to the cuff locking device 10, the axially rotatable coupling between the projecting pin 14 of the fixing plate 12 and the lower end 13 b of the connecting arm 13 allows cuff 5 to freely move/rotate with respect to shell 2 on a second reference plane P locally orthogonal to the vertical centre-plane of the boot. Accordingly, any structural constraint is eliminated, which may prevent the hinges 6 from varying the tilt angle of axis A with respect to the vertical centre-plane of the boot.

Several advantages are achieved with the particular structure of the cuff locking device 10. Firstly, the cuff locking device 10 allows wide range of adjustment of the lateral tilt angle of cuff 5, while simultaneously eliminating all those mechanical clearances that compromise the proper operation of the cuff locking device 10.

In other words, the particular structure of the cuff locking device 10 allows the comfort of the footwear to be significantly improved without however compromising the dynamic behaviour of the boot when it is used in downhill skiing. Contrarily, the lack of angular limits in the adjustment of the lateral tilt angle of cuff 5 allows the travel of the hinges 6 to be significantly extended, thus increasing the possibilities of personalizing boot 1.

Furthermore, when the cuff locking device 10 is configured so as to leave cuff 5 free to swing on shell 2 about axis A, no parts of the cuff locking device 10 drag on one another thus opposing in some way the user's movement.

Moreover, the cuff locking device 10 is also suitable to be mounted on already marketed mountaineering ski and Telemark ski boots with small mechanical adaptations.

Lastly but no less importantly, the cuff locking device 10 allows the supporting plate 11 and the components which are integral therewith (i.e. the connecting arm 13 and the arm lifting mechanism 19) to be easily removed, and cuff 5 to be directly and permanently rigidly connected to the fixing plate 12 by means of a second connecting arm 23, with the weight reduction resulting therefrom.

Indeed, the weight of the second connecting arm 23 is sensibly less than the overall weight of supporting plate 11, connecting arm 13 and arm lifting mechanism 19.

Lastly, it is apparent that modifications and variants may be made to the above-described mountaineering ski and Telemark ski boot 1, without departing from the scope of the present invention.

For example, in a less sophisticated embodiment, the supporting plate 11 could be fixed to the rear part of cuff 5 in a non-removable manner, or be made in one piece with cuff 5.

In other words, in this embodiment, the cuff locking device 10 comprises: the fixing plate 12, again arranged on shell 2 substantially at the heel of the boot; and the connecting arm 13 which, in the area immediately above the heel of the boot, extends astride between the rear part of cuff 5 and the fixing plate 12, while remaining on a lying plane substantially perpendicular to the articulation axis A of hinges 6, and is hinged on the rear part of cuff 5 so as to oscillate with respect to cuff 5 about a second reference axis B locally substantially perpendicular to the lying plane of the connecting arm 13. 

1. Ski boot comprising a rigid shell which is shaped so as to accommodate the foot of the user, and a rigid cuff which is shaped so as to enclose the ankle of the user and is hinged on the shell so as to rotate about a first axis substantially perpendicular to the center-plane of the boot and locally substantially coincident with the articulation axis of the ankle of the user; the ski boot being also provided with a cuff locking device which is structured so to selectively rigidly lock the cuff to the shell so as to prevent any movement between the two components, or release the cuff from the shell so as to allow the cuff to freely swing about said first axis while remaining substantially on the center-plane of the boot; the ski boot being characterised in that the cuff locking device comprises: a fixing plate which is located on the shell substantially at the heel of the boot; and a connecting arm which, in the area above the heel of the boot, extends astride between the rear part of the cuff and the fixing plate, while remaining on a lying plane substantially perpendicular to said first axis, and is hinged on the rear part of the cuff so as to oscillate with respect to the cuff about a second axis locally substantially perpendicular to the lying plane of the same connecting arm; the fixing plate being also provided with a projecting pin which protrudes from the shell while remaining coaxial to a third axis which lies substantially on the center-plane of the boot, ad is tilted with respect to the vertical by an angle ranging between 60° and 90°; the lower end of the connecting arm instead being shaped/structured so as to be selectively insertable/fittable on the projecting pin of the fixing plate in an axially rotatable and easily releasable/extractable manner, so as to constrain the connecting arm to the fixing plate with the sole possibility of freely rotating about said third axis.
 2. Ski boot according to claim 1, characterised in that the lower end of the connecting arm is provided with a slot or eyelet which is shaped so as to be engaged in an axially rotatable and sliding manner by said projecting pin, so as to constrain the connecting arm to the fixing plate with the sole possibility of freely rotating with respect to the fixing plate about the projecting pin.
 3. Ski boot according to claim 2, characterised in that the projecting pin has a substantially circular section, and the slot or eyelet has a circular section substantially complementary to that of said projecting pin.
 4. Ski boot according to claim 1, characterised in that the cuff locking device also comprises a manually-operated arm lifting mechanism which is structured so as to selectively and alternatively arrange the connecting arm in a totally lowered position in which the lower end of the connecting arm is fitted/inserted on the projecting pin of the fixing plate, so as to prevent any swinging of the cuff on the shell about said first axis; and in a totally lifted position in which the lower end of the connecting arm is completely extracted and spaced from the projecting pin of the fixing plate, so as to allow the cuff to freely swing on the shell about said first axis.
 5. Ski boot according to claim 4, characterised in that the arm lifting mechanism comprises an elastic member which is structured so as to elastically maintain the connecting arm stably in the totally lowered position; and a manually-operated control member which can displace and stably maintain the connecting arm in the totally lifted position overcoming the elastic thrust of said elastic member.
 6. Ski boot according to claim 5, characterised in that said manually-operated control member is a lever which is hinged on the connecting arm, and is shaped/structured so as to prop on the immediately underlying body of the cuff to force the connecting arm to rotate about the second axis from the totally lowered position to the totally lifted position overcoming the thrust of the elastic member.
 7. Ski boot according to claim 6, characterised in that said lever is hinged on the connecting arm so as to freely rotate on the connecting arm while remaining on a reference plane locally substantially parallel or coincident with the lying plane of the connecting arm.
 8. Ski boot according to claim 1, characterised in that the cuff locking device also comprises a supporting plate which is rigidly fixed on the rear part of the cuff, above the heel of the boot, so as to substantially lie on the center-plane of the boot, and the connecting arm is hinged on said supporting plate.
 9. Ski boot according to claim 8, characterised in that the supporting plate is fixed on the rear part of the cuff in a rigid and stable, though easily removable, manner.
 10. Ski boot according to claim 9, characterised in that the supporting plate is also structured to be fixable on the rear part of the cuff in a plurality of distinct anchoring positions which are freely selectable by the user.
 11. Ski boot according to claim 9, characterised in that the cuff locking device also comprises a second connecting arm which has a first end structured so to be fixable in a rigid and stable, though easily releasable, manner on the rear part of the cuff, in place of the supporting plate, and a second end shaped/structured so as to be insertable/fittable on the projecting pin of the fixing plate in an axially rotatable and easily releasable/extractable manner, so as to constrain the connecting arm to the fixing plate with the sole possibility of freely rotating about the axis of the projecting pin.
 12. Ski boot according to claim 11, characterised in that the first end of said second connecting arm is structured to be fixable on the rear part of the cuff in a plurality of distinct anchoring positions which are freely selectable by the user.
 13. Ski boot according to claim 1, characterised in that the cuff is fixed in a freely rotatable manner on the shell by means of two connection hinges which are arranged on the external and internal lateral sides of the shell and of the cuff, aligned along said first axis; said connection hinges being structured so as to allow a manual adjustment of the tilt angle of said first axis with respect to the center-plane of the boot.
 14. Ski boot according to claim 1, characterised in that the shell and/or the cuff are made of plastic or composite material. 